The results of the analysis discussed in detail below indicate that we can expect the 100-year flood elevation at Fort Point in New Castle, NH to increase from a current elevation of 11.2 feet to a range of 12.4 to 13.1 feet by 2050, and to a range of 14.0 to 17.8 feet by 2100. Therefore, even under low greenhouse gas emissions scenarios, we can expect the 100-year flood elevation to increase several feet over the next 90 years. This increase in the 100-year flood elevation will result in more severe flooding in coastal New Hampshire in the future.

To illustrate the impact of the higher 100-year flood elevations in the future, we have produced a series of ten maps that cover the NH seacoast, Piscataqua River, and Great Bay. These maps show stillwater flood depths over land for flood elevations of six feet, nine feet, and twelve feet above mean higher high water (MHHW). (MHHW is the average of the higher high water elevation of each tidal day; values are provided by NOAA.)